Method, system, and apparatus for flood control

ABSTRACT

A dynamic fluid flow control structure is provided that allows precise control over fluid flow using a series of two or more orifices, at least one of which may be reconfigured to change its flow characteristics. A flood control system and a flood control process are provided that emulate a preset discharge profile over time. Some versions of the structure, process, and system can be used to provide controlled storm discharge patterns in a developed area that emulate the natural pre-development discharge patterns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage under 35 U.S.C. 371 ofInternational Application PCT/US2013/73671, filed on Dec. 6, 2013(currently pending). International Application PCT/US2013/73671 citesthe priority of U.S. Patent Application 61/739,555, filed Dec. 19, 2012(currently pending).

BACKGROUND

A. Field of the Disclosure

The present disclosure relates generally to flood control. Morespecifically, the disclosure relates to the control of the discharge offlood waters from a source body of water.

B. Background

Controlling the effects of flood events has long been an engineeringchallenge. The development of agricultural areas or wild areasinevitably changes the patterns of runoff into streams during rainfallevents. During the course of development permeable soil is covered withbuildings and roads, which are impermeable to water. As a result, theflow of water that hits the ground as precipitation is not slowed bypercolation into the ground. This causes runoff to enter rivers andstreams at very high rates of volumetric discharge in developed areas.The attendant runoff problems can cause flooding of downstream areas,erosion, and non-point source pollution of rivers and streams.

The conventional approach to controlling runoff from precipitationevents is to provide a static flood control structure. In the absence offlood control structures, runoff from a developed area will usuallyoccur at an extremely high initial rate (“peak flow”) and then declineabruptly. Static flood control structures, such as dams and weirs,reduce the peak flow rate and cause the flow to taper off slowly.

Static control structures typically consist of a fixed opening that isdesigned to restrict the discharge flow rate for a hypothetical designstorm event. Of course, a design storm event will never occur. Designstorms are based on statistical data compiled over the course of severalyears from weather stations and other sources. One commonly used processfor developing the design storm events is described in a documentpublished by the United States Department of Commerce prepared for theNatural Resources Conservation Service, often referred to as TechnicalPaper 40 (TP40), published May 1961. This document is widely used forcontrolling storm water runoff for post-developed watersheds.

Although static controls reduce the impacts of developmentsignificantly, they do not emulate the natural pre-development flowpatterns in response to precipitation. The standard of practice in sitedevelopment is to restrict the post-developed peak flow rate topre-developed peak flow rate conditions for a hypothetical design stormevent. This results in gradual decline in the recession limb of thehydrograph consequently resulting in higher discharge velocities andhigher discharge flow rates over the duration of the storm event.

Natural flow patterns are more desirable than the types of lessattenuated patterns that static control structures provide. In additionto reducing erosion, downstream flooding, and non-point sourcepollution, natural flow patterns serve to maintain waterlogged (hydric)soils that form and maintain wetlands. The wetlands in turn mitigatefloods, remove pollutants, and spawn wildlife. Static control structurescannot emulate natural flow. The natural flow patterns from a givendrainage area are the result of many complex interacting factors, suchas heterogeneous soil porosity, the presence (or absence) of impermeablesoil layers, and topography. Furthermore, natural flow patterns willvary with the severity of a precipitation event. Current controlstructure designs are generated from idealized “design storm events.”Design storm events are created from hypothetical methods calculatedfrom historical data. These data, being generated by mathematicalmodels, may not reflect the variations of depth, intensity, anddurations of actual precipitation events. Furthermore, the rate ofdischarge of static control structures is a direct function to thehydrostatic pressure (also known as “head,” which is directly related todepth) in the detention body, making it impossible to replicatepre-developed hydrology.

Consequently there is a need in the art to provide natural flow patternseven after areas have been developed.

SUMMARY

A dynamic fluid flow control structure 1 is provided which providesincremental flow control (as opposed to continuous flow control). In ageneral embodiment, the fluid flow control structure 1 comprises: aconduit 100 through which the fluid flows; an upstream reconfigurablebarrier 200 in the conduit 100, the upstream barrier 200 comprising anupstream orifice 210, and the upstream barrier 200 capable of assuming afirst upstream configuration and a second upstream configuration; adownstream barrier 300 in the conduit 100, the downstream barrier 300comprising a downstream orifice 310; wherein the upstream orifice 210restricts the flow of the fluid more than does the downstream orifice310 when the upstream barrier 200 assumes the first configuration, andwherein the upstream orifice 210 restricts the flow of the fluid no morethan does the downstream orifice 310 when the upstream barrier 200assumes the second configuration.

Another general embodiment the fluid flow control structure 1 comprisesa means for providing a first orifice 600 in the path of the fluid flow;a means for providing a second orifice 700 orifice larger than the firstorifice in the path of the fluid flow downstream from the first orifice;and a structure selected from the group consisting of: (i) a means forexpanding the first orifice 800 to a size greater than the size of thesecond orifice; and (ii) a means for removing the first orifice 900 fromthe path of the fluid flow.

A method of controlling fluid flow through a conduit 100 is provided,wherein the conduit 100 comprises an upstream orifice 210 and adownstream orifice 310, the method comprising: reconfiguring theupstream orifice 210 from a configuration in which the upstream orifice210 reduces the flow of the fluid more than does the downstream orifice310 to a configuration in which the upstream orifice 210 reduces theflow of the fluid no more than does the downstream orifice 310.

A flood control system 3000 is provided. A general embodiment of theflood control system 3000 comprises means for variably controlling therate of volumetric discharge 1600 from an intake point to a releasepoint; means for automated control 1700 of the means for variablycontrolling the rate of volumetric discharge 1600; means for measuringthe water level 1800 at the intake point that transmits water level datato the means for automated control 1700; means for measuring rainfall1900 that transmits rainfall data to the means for automated control1700; and means for storing a storm discharge function 1410 that isreadable by the means for automated control 1700.

Another general embodiment of the flood control system 3000 comprises aflow control structure 1000 configured to variably control the rate ofvolumetric discharge from an intake point to a release point; acomputing device 1100 in control of the flow control structure 1000; awater level meter 1200 positioned to measure the water level at theintake point and configured to transmit water level data to thecomputing device 1100; a rain gauge 1300 configured to transmit rainfalldata to the computing device 1100; and a machine-readable data storagedevice 1400 comprising a storm discharge function 1410, wherein themachine-readable data storage device 1400 is configured to be read bythe computing device 1100.

A process for controlling discharge from a body of water during a stormevent is provided, the process comprising: reading a storm dischargefunction 1410 from a machine-readable storage device, wherein the stormdischarge function 1410 sets a rate of volumetric discharge as afunction of rainfall rate; computing a target rate of volumetricdischarge by plugging a rainfall rate value into the function; andconfiguring a flow control structure 1000 to provide approximately thetarget rate of volumetric discharge from the body of water. Amachine-readable storage device is provided containing a program whichwhen read by a computing device causes the computing device to performthis process.

The above presents a simplified summary in order to provide a basicunderstanding of some aspects of the claimed subject matter. Thissummary is not an extensive overview. It is not intended to identify keyor critical elements or to delineate the scope of the claimed subjectmatter. Its sole purpose is to present some concepts in a simplifiedform as a prelude to the more detailed description that is presentedlater.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A cross-sectional illustration of an embodiment of the dynamicflood control structure 1.

FIG. 2: An illustration of the longitudinal cross-section from FIG. 1(labeled FIG. 2).

FIG. 3: An illustration of the longitudinal cross-section from FIG. 1(labeled FIG. 3).

FIG. 4: A perspective view of an embodiment of the reconfigurablebarriers comprising two retractable sections 220, the view showing onlyone section of each barrier and not showing the rest of the floodcontrol structure 1.

FIG. 5: A perspective view of an embodiment of a single reconfigurablebarrier, which serve as the upstream reconfigurable barrier 200/600 orthe intermediate reconfigurable barrier 400; not showing the rest of theflood control structure 1.

FIG. 6: An exploded view of the embodiment of the reconfigurable barriershown in FIG. 5.

FIG. 7: A frontal plan view of an embodiment of the dynamic floodcontrol structure showing a series 500 of intermediate reconfigurablebarriers 400 in their expanded configurations, such that theintermediate orifices are all larger than the downstream orifice 310.

FIG. 8: A perspective view of en embodiment of the flood control system.

FIG. 9: Modeled results of discharge over time from a retaining body toa receiving water during a two-year storm event in a developed basinthat was previously undeveloped. The top frame compares uncontrolledpost-developed discharge to pre-developed discharge. The middle frameshows a comparison of post-developed discharge controlled by a staticflood control structure to pre-developed discharge. The bottom frameshows a comparison of post-developed discharge controlled according toan embodiment of the flood control method provided in this applicationto pre-developed discharge.

FIG. 10: Modeled results of discharge over time for the same drainagebasin as in FIG. 9, but for a 25-year storm event. The top framecompares uncontrolled post-developed discharge to pre-developeddischarge. The middle frame shows a comparison of post-developeddischarge controlled by a static flood control structure topre-developed discharge. The bottom frame shows a comparison ofpost-developed discharge controlled according to an embodiment of theflood control method provided in this application to pre-developeddischarge.

FIG. 11: Modeled results of discharge over time for the same drainagebasin as in FIGS. 9 and 10, but for a 100-year storm event. The topframe compares uncontrolled post-developed discharge to pre-developeddischarge. The middle frame shows a comparison of post-developeddischarge controlled by a static flood control structure topre-developed discharge. The bottom frame shows a comparison ofpost-developed discharge controlled according to an embodiment of theflood control method provided in this application to pre-developeddischarge.

FIG. 12: Modeled results and actual measurements of a historical stormevent for the same developed drainage basin as in FIGS. 9-11. The topframe compares uncontrolled post-developed discharge to pre-developeddischarge. The middle frame shows a comparison of post-developeddischarge controlled by a static flood control structure topre-developed discharge. The bottom frame shows a comparison ofpost-developed discharge controlled according to an embodiment of theflood control method provided in this application to pre-developeddischarge.

DETAILED DESCRIPTION

A. Definitions

With reference to the use of the word(s) “comprise” or “comprises” or“comprising” in the foregoing description and/or in the followingclaims, unless the context requires otherwise, those words are used onthe basis and clear understanding that they are to be interpretedinclusively, rather than exclusively, and that each of those words is tobe so interpreted in construing the foregoing description and/or thefollowing claims.

The terms “about” or “approximately” mean within a range of reasonableerror around a central value. Such reasonable error may for example stemfrom the precision of an instrument or method used to measure the value.The error could also stem from the precision of a method of making acomposition, such as the ability to measure particular ingredientswithin a margin of error.

The term “machine-readable data storage device” or “data storage device”as used herein refers to a machine-readable device that retains datathat can be read by mechanical, optical, or electronic means, forexample by a computer. Such devices are sometimes referred to as“memory,” although as used herein a machine-readable data storage devicecannot comprise a human mind in whole or in part, including humanmemory. A storage device may be classified as primary, secondary,tertiary, or off-line storage. Examples of a storage device that isprimary storage include the register of a central processing unit, thecache of a central processing unit, and random-access memory (RAM) thatis accessible to a central processing unit via a memory bus (generallycomprising an address bus and a data bus). Primary storage is generallyvolatile memory, which has the advantage of being rapidly accessible. Astorage device that is secondary storage is not directly accessible tothe central processing unit, but is accessible to the central processingunit via an input/output channel. Examples of a storage device that issecondary storage include a mass storage device, such as a magnetic harddisk, an optical disk, a drum drive, flash memory, a floppy disk, amagnetic tape, an optical tape, a paper tape, and a plurality of punchcards. A storage device that is tertiary storage is not connected to thecentral processing unit until it is needed, generally accessedrobotically. Examples of a storage device that is tertiary storage maybe any storage device that is suitable for secondary storage, butconfigured such that it is not constantly connected to the centralprocessing unit. A storage device that is off-line storage is notconnected to the central processing unit, and does not become soconnected without human intervention. Examples of a storage device thatis off-line storage may be any storage device that is suitable forsecondary storage, but configured such that it is not constantlyconnected to the central processing unit, and does not become soconnected without human intervention. Secondary, tertiary, and offlinestorage are generally non-volatile, which has the advantage of requiringno source of electrical current to maintain the recorded information.

The term “machine-readable media” as used herein refers to a medium ofstoring information that is configured to be read by a machine. Suchformats include magnetic media, optical media, and paper media (punchcards, paper tape, etc.). Printed writing in a human language, if notintended or configured to be read by a machine, is not considered amachine readable format. In no case shall a human mind be construed as“machine readable format.”

Neither a storage device nor machine-readable media can be construed tobe a mere signal, although information may be communicated to and from astorage device or machine-readable media via a signal.

The term “database” as used herein refers to an organized data structurecomprising a plurality of records stored in machine-readable format.

The term “variable” as used herein refers to a symbolic namecorresponding to a binary value stored at a given memory address on adata storage device (although this address may change). The binary valuemay represent information of many types, such as integers, real numbers,Boolean values, characters, and strings, as is understood in the art. Asused herein the value of a variable is always stored in a data storagedevice, and shall not be construed to refer to information only storedin a human mind. Any recitation of a variable implicitly requires theuse of a data storage device.

The terms “about” or “approximately” mean within a range of reasonableerror around a central value. Such reasonable error may for example stemfrom the precision of an instrument or method used to measure the value.The error could also stem from the precision of a method of making acomponent of a device.

B. Fluid Flow Control Structure

A dynamic fluid flow control structure 1 is provided. In a generalembodiment (and as illustrated in FIGS. 1-7), the structure comprises aseries of barriers each comprising an orifice, the orifices decreasingin the degree to which they restrict flow as a function of pressure, inthe direction of the flow (from the upstream-most orifice to thedownstream-most orifice). This restriction in flow is a function of thesize of the orifice, the shape of the orifice, or both. The structurefunctions to control the volumetric rate of flow (also known as“discharge,” Q) by directing the fluid flow through a more restrictiveorifice (either of smaller size or of a shape that restricts flow) thatis upstream of one or more less restrictive orifices (larger or of lessrestrictive shape). The flow of the fluid will be a function of changein hydrostatic head (h) between the upstream and downstream end of thestructure, the diameter (D) of the most restrictive orifice throughwhich the fluid must flow, and the cross-sectional area (A) of the mostrestrictive orifice through which the fluid must flow. To increase Q ata given h, the most restrictive orifice in the structure is effectivelyremoved. In this context “effectively removed” means that the mostrestrictive orifice is either expanded in size or altered in shape suchthat it is no longer the most restrictive orifice in the structure, orthe most restrictive orifice may be removed entirely from the device(for example by moving the barrier in which the orifice resides out ofthe flow of the fluid). This will effectively increase D or A for theorifice (or both), which will increase Q at a given h.

The basic physics of the control structure are provided below. Althoughthe description provided below assumes that the structure is used tocontrol flow from an open body of water to an unsubmerged receivingpoint, it should be understood that the uses of the control structureare not limited to such scenarios.

Flows that do not submerge the receiving point may be modeled as weirflow and such flows are considered an “unsubmerged condition.” Withoutwishing to be bound by any given hypothetical model, the equation forunsubmerged orifice flow for the structure is:Q=AD ^(0.5){(h−H _(c) −C _(s) D)(KD)⁻¹}^((l/m))  eq. 1

A=cross-sectional area of the orifice;

D=diameter of the orifice;

h=depth of source water;

H_(c)=specific energy at critical depth (H_(c)=Y_(c)+V²/2g);

C_(s)=slope correction factor;

K, m=constants determined by the shape of the orifice.

Equation 1 is found in the United States Federal Highway Administrationpublication “Hydraulic Design of Highway Culverts” HDS-5. Duringunsubmerged conditions the depth of flow just past the orifice reachescritical depth. Under conditions in which the orifice is completelysubmerged flow through the orifice can be modeled as follows:Q=C _(d) A(2gh)^(0.5)  eq. 2in which C_(d) is the coefficient of discharge and g is acceleration dueto gravity. Under more generalized circumstances, when flow is driven bya pressure differential between two ends of the conduit, submergedorifice flow can be modeled as follows:Q=C _(d) A(2ΔP/ρ)^(0.5)  eq. 3in which ΔP is the difference in pressure between the inlet and theoutlet of the structure and in which ρ is the density of the fluid.Assuming the orifice is of constant size and shape, and assuming thatthe slope of the conduit is also constant, discharge is a function ofthe depth of the source water. When the source water is at a givendepth, discharge can be modulated by changing the size of the orifice,the shape of the orifice, or both.

In the above equation Q is proportional to the cross-sectional area A ofthe orifice such that as Q increases the orifice diameter increases.Using an orifice with a given area and shape, assuming that the densityof the water is constant (which is true under the conditions relevant toflood control applications), Q becomes a function of the depth of thesource water. Under conditions in which the depth of the source water isconstant, and the size of the orifice may be varied (but the shape doesnot vary), Q will be a function of cross-sectional area of the orifice.

These properties can be used to regulate discharge in a flow controlstructure 1 comprising a plurality of barriers each having an orifice ofroughly the same shape, in which each orifice has a minimum size whichis smaller than the minimum size of the next orifice downstream in theseries. Discharge from the structure is dependent only on the size ofthe smallest orifice through which the fluid flows. Because thestructure varies the smallest orifice size incrementally by effectivelyremoving the smallest orifice in the series, the structure will varydischarge incrementally, as opposed to continuously. Of course, the sametype of control could be achieved by providing orifices of varyingshapes (or of varying shapes and sizes), although such structures wouldbe more complex in design.

Conventional designs for variably controlling flow rely on flow controldevices that constantly vary discharge by constantly varying the size ofan opening through which the fluid flows, such as valves and gates. Aconsequence of this approach is that in order to precisely determinedischarge, one must know the precise degree to which the valve or gateis open (more accurately, one must precisely know the size and shape ofthe opening created by the valve or gate). It is very difficult tomonitor the exact degree to which a valve or gate is open without theuse of a sensor. In addition, sensors often require periodic calibrationif they are to provide accurate measurements. If the exact degree towhich the valve or gate is open cannot be readily ascertained, then theresulting discharge cannot be predicted with any degree of precision.Those embodiments of the structure that provide incremental control ofdischarge provide a technologically simple means to control dischargewith greater precision. Some embodiments of the structure function tocontrol the flow of a liquid. The liquid may be an incompressibleliquid, water being one example.

In all general embodiments, as many barriers will be present asnecessary to provide the desired range of discharge. Some embodiments ofthe structure 1 comprise one barrier. Other embodiments comprise two ormore barriers. Specific embodiments comprise at least 3, at least 4, andat least 16 barriers. In a further specific embodiment the structurecomprises at least 36 barriers. In a further specific embodiment thestructure comprises at least 72 barriers. In some embodiments of thedevice the orifices increase in diameter in the downstream direction byan approximately uniform increment; the increment may be, for example,about ½″-6″ (or exactly this range). The increment may be any sub-rangeof ½″-6″. In a specific embodiment the increment is ½″.

A general embodiment of the structure 1 comprises a fluid conduit 100through which the fluid flows; an upstream reconfigurable barrier 200 inthe conduit 100, the upstream barrier 200 comprising an upstream orifice210, and the upstream barrier 200 capable of assuming a first upstreamconfiguration and a second upstream configuration; a downstream barrier300 in the conduit 100, the downstream barrier 300 comprising adownstream orifice 310; wherein the upstream orifice 210 restricts theflow of the fluid more than does the downstream orifice 310 when theupstream barrier 200 assumes the first configuration, and wherein theupstream orifice 210 restricts the flow of the fluid no more than doesthe downstream orifice 310 when the upstream barrier 200 assumes thesecond configuration.

An alternate general embodiment of the structure comprises means forproviding a first orifice 600 in the path of the fluid flow; means forproviding a second orifice 700 larger than the first orifice 600 in thepath of the fluid flow downstream from the first orifice; and astructure selected from the group consisting of: (i) means for expandingthe first orifice 800 to a size greater than the size of the secondorifice; and (ii) means for removing the first orifice 900 from the pathof the fluid flow. The means for providing the first orifice 600 may be,for example, the upstream barrier 200. The means for providing thesecond orifice 700 may be, for example, the downstream barrier 300. Themeans for expanding the first orifice 800 may be any suitable structuredescribed below; and the means for removing the first orifice 900 may beany suitable structure described below.

In this context a first orifice “restricts” the flow of the fluid morethan another orifice if the discharge of the fluid through the firstorifice (Q₁) is lower than the discharge of the fluid though the otherorifice (Q₂) under otherwise identical conditions (i.e., same ΔP, sameconduit 100 diameter, same C_(d), same depth of the source water). Underconditions in which equation 2 controls, a first orifice “restricts” theflow of the fluid more than another orifice if the C_(d)A value of thefirst orifice is smaller than the C_(d)A value of the other orifice. Ifboth orifices are of the same shape, the first orifice will have asmaller diameter and a smaller cross-sectional area than the otherorifice. Thus, in some embodiments of the structure, the upstreamorifice 210 has a lesser upstream C_(d)A value when the upstream barrier200 assumes the first upstream configuration; the upstream orifice 210has a greater upstream C_(d)A value when the upstream barrier 200assumes the second upstream configuration; the downstream orifice 310has a downstream C_(d)A value; the lesser upstream C_(d)A value issmaller than the greater upstream C_(d)A value; the lesser upstreamC_(d)A value is less than the downstream C_(d)A value; and the greaterupstream C_(d)A value is not less than the downstream C_(d)A value.

Some embodiments of the upstream orifice 210 will be designed to vary insize so as to control fluid flow. In such embodiments the upstreamorifice 210 is a contracted upstream size when the upstream barrier 200assumes the first upstream configuration; the upstream orifice 210 is anexpanded upstream size when the upstream barrier 200 assumes the secondupstream configuration; the downstream orifice 310 is a downstreamorifice 310 size; the contracted upstream size is smaller than theexpanded upstream size; the contracted upstream size is smaller than thedownstream orifice 310 size; and the expanded upstream size is nosmaller than the downstream orifice 310 size. The shape of the upstreamorifice 210 and the downstream orifice 310 will have about the sameratio of diameter to cross-sectional area in some such embodiments(resulting in about the same C_(d)A if the two orifices are about thesame size). In these embodiments the upstream barrier 200 isreconfigured to increase or decrease the size of the upstream orifice210. This can be accomplished by various means of expanding andcontracting an orifice as known in the art. For example, the upstreamorifice 210 may be expanded and contracted using an iris valve or a gatevalve.

Specific embodiments of the reconfigurable upstream barrier 200 comprisea plurality of retractable sections 220. The sections are “retractable”in that they may be retracted away from one another to increase the sizeof the orifice (and in most embodiments the retractable sections 220 canthen be extended toward one another). The upstream reconfigurablebarrier 200 may comprise two retractable sections 220. Some versions ofthe upstream barrier 200 can be reconfigured such that the tworetractable sections 220 are retracted at least partially from theconduit 100 in the second upstream configuration and are fully extendedinto the conduit 100 in the first upstream configuration.

In some embodiments the retractable sections 220 themselves will atleast partially define the rim of the orifice. In some such embodiments,the upstream reconfigurable barrier 200 comprises two retractablesections 220 that are retracted at least partially from the conduit 100in the second upstream configuration and that are fully extended intothe conduit 100 in the first upstream configuration; and each of the tworetractable sections 220 define a portion of the perimeter of theupstream orifice 210. Each of the two retractable sections 220 maydefine half of the perimeter of the upstream orifice 210. In a specificembodiment the upstream reconfigurable barrier 200 comprises tworetractable sections 220 that each define a semicircular portion of acircular orifice 210 such that when extended into contact with oneanother, they create a circular orifice in the barrier 200. In otherrelated embodiments the retractable sections 220 each define half of anorifice 210 of another shape, for example an orifice that is arectangle, square, polygon, oval, or an ellipse. If the reconfigurablebarrier 200 comprises more than two retractable sections 220, then eachretractable section 220 may define a portion of the perimeter of theorifice 210. In some embodiments each of the more than two retractablesections 220 will define an equal fraction of the portion of theperimeter of the orifice 210. For example, if three retractable sections220 are used they may each define one third of the perimeter of theorifice 210; if four retractable sections 220 are used they may eachdefine one quarter of the perimeter of the orifice 210; and so on.

The sections 220 may be extended and retracted by any means known in theart. For example, given sections 220 may be slid toward and away fromone another in a direction perpendicular to the direction of flow. Suchembodiments have the advantage of never moving the sections 200 againstthe flow of the fluid. The sections 220 may be slid along tracks thatare recessed in the conduit 100. In a specific embodiment thereconfigurable barrier comprises two retractable sections 220, each ofwhich is connected to a threaded rod that may be rotated in eitherdirection to retract or extend each section 220.

In some embodiments of the reconfigurable barrier 200 in which theupstream orifice 210 assumes a contracted and expanded size (in thefirst and second configurations, respectively), the upstream orifice 210is maximally contracted in the first upstream configuration. In someembodiments, the upstream orifice 210 is maximally expanded in thesecond upstream configuration. In more specific embodiments the upstreamorifice 210 is maximally contracted in the first upstream configurationand the upstream orifice 210 is maximally expanded in the secondupstream configuration. In such embodiments the orifice can be placed inthe first configuration by contracting it as much as possible, andplaced in the second configuration by expanding it as much as possible.This eliminates the need to assess the degree to which the orifice 210is expanded or contracted in order to determine the extent to which theorifice 210 restricts the flow of the fluid. In some embodiments of thestructure, the upstream reconfigurable barrier 200 is inserted into theconduit 100 when in the first upstream configuration and the upstreamreconfigurable barrier 200 is withdrawn from the conduit 100 when in thesecond upstream configuration. Thus, instead of varying the size orshape of the orifice 210, the barrier 200 is reconfigured by removingthe barrier 200 and the orifice 210 from the conduit 100 altogether.

Some embodiments of the structure 1 comprise an intermediatereconfigurable barrier 400. Such embodiments comprise an intermediatereconfigurable barrier 400 in the conduit 100 between the upstreambarrier 200 and the downstream barrier 300. The intermediate barrier 400comprises an intermediate orifice 410, and the intermediate barrier 400is capable of assuming a first intermediate configuration and a secondintermediate configuration. The intermediate orifice 410 restricts theflow of the fluid more than does the downstream orifice 310 when theintermediate barrier 400 assumes the first configuration. Theintermediate orifice 410 restricts the flow of the fluid no more thandoes the downstream orifice 310 when the intermediate barrier 400assumes the second configuration. The upstream orifice 210 restricts theflow of the fluid more than does the intermediate orifice 410 when theupstream barrier 200 assumes the first configuration and theintermediate barrier 400 assumes the first configuration. The upstreamorifice 210 restricts the flow of the fluid no more than does theintermediate orifice 410 when the upstream barrier 200 assumes thesecond configuration and the intermediate orifice 410 assumes the firstconfiguration. Consequently, the intermediate barrier 400 can functionto provide an intermediate level of flow control (allowing less flowthan the upstream barrier 200, but more than the downstream barrier300).

Some embodiments of the intermediate barrier 400 can be reconfigured toexpand or contract the size of the intermediate orifice 410. In suchembodiments of the intermediate barrier 400, the intermediate orifice410 is a contracted intermediate size when the intermediate barrier 400assumes the first intermediate configuration, and the intermediateorifice 410 is an expanded intermediate size when the intermediatebarrier 400 assumes the second intermediate configuration. In someembodiments of the device in which the intermediate orifice 410 may beexpanded or contracted, the upstream orifice 210 is a contractedupstream size when the upstream barrier 200 assumes the first upstreamconfiguration, and the upstream orifice 210 is an expanded upstream sizewhen the upstream barrier 200 assumes the second upstream configuration.The downstream orifice 310 can be said to have a downstream orifice 310size. The contracted upstream size is smaller than the expanded upstreamsize. The contracted intermediate size is smaller than the expandedintermediate size. The contracted upstream size is smaller than thecontracted intermediate size. The contracted intermediate size issmaller than the downstream orifice 310 size. The expanded upstream sizeis no smaller than the downstream orifice 310 size. The expandedintermediate size is no smaller than the downstream orifice 310 size.Thus, neither the upstream 210 nor intermediate 410 orifices in theirexpanded configurations are smaller than the downstream orifice 310,although both are smaller in their contracted configurations than thedownstream orifice 310. When the intermediate orifice 410 is contractedit is larger than the upstream orifice 210 when it is contracted.

In the above description, the C_(d)A value can serve to replace anymention of “size,” although it is to be understood that the C_(d)A valuecan be affected by shape as well as by size. Taking into considerationthe role of the C_(d)A value in determining the rate of dischargethrough an orifice, in some embodiments of the structure the upstreamorifice 210 has a lesser upstream C_(d)A value when the upstream barrier200 assumes the first upstream configuration, and the upstream orifice210 has a greater upstream C_(d)A value when the upstream barrier 200assumes the second upstream configuration. The lesser upstream C_(d)Avalue is smaller than the greater upstream C_(d)A value. The downstreamorifice 310 may be said to have a downstream C_(d)A value. Theintermediate orifice 410 has a lesser intermediate C_(d)A value when theintermediate barrier 400 assumes the first intermediate configuration;and a greater intermediate C_(d)A value when the intermediate barrier400 assumes the second intermediate configuration. The lesserintermediate C_(d)A value is smaller than the greater intermediateC_(d)A value. The lesser upstream C_(d)A value is smaller than thelesser intermediate C_(d)A value; the lesser intermediate C_(d)A valueis smaller than the downstream C_(d)A value; the greater upstream C_(d)Avalue is no smaller than the downstream C_(d)A value; and the greaterintermediate C_(d)A value is no smaller than the downstream C_(d)Avalue.

In an alternative embodiment of the intermediate barrier 400, theintermediate reconfigurable barrier 400 is inserted into the conduit 100when in the first intermediate configuration and the intermediatereconfigurable barrier 400 is withdrawn from the conduit 100 when in thesecond intermediate configuration. As described for the upstream barrier200 above, in these embodiments the barrier is simply removed from thefluid flow instead of being reconfigured to change the size or shape ofthe orifice.

Some embodiments of the structure comprise a series 500 ofreconfigurable intermediate barriers 400 between the upstream 200 anddownstream 300 barriers each comprising an intermediate orifice 410. Insuch embodiments each of the intermediate barriers 400 have a firstintermediate configuration, a second intermediate configuration, and agiven intermediate orifice 410 restricts the flow of the fluid more thandoes the orifice immediately downstream when the given intermediatebarrier 400 assumes the first intermediate configuration. The givenintermediate orifice 410 reduces the flow of the fluid no more than doesthe orifice immediately downstream when the given intermediate barrier400 assumes the second configuration. Such embodiments of the deviceallow incremental control of the rate of discharge of the fluid throughthe conduit 100 by reconfiguring each intermediate barrier 400 as neededsuch that the upstream-most intermediate barrier 400 restricts the flowto a greater extent than any barrier downstream.

As in the intermediate barrier 400 described above, each of the seriesof intermediate barriers 400 may be reconfigured by expanding orcontracting the orifice. In some embodiments of the structure eachintermediate orifice 410 is a contracted intermediate size when theintermediate barrier 400 assumes the first intermediate configurationand each intermediate orifice 410 is an expanded intermediate size whenthe intermediate barrier 400 assumes the second intermediateconfiguration. In such embodiments the contracted intermediate size of agiven intermediate orifice 410 is smaller than the size of the orificeimmediately downstream; and the expanded intermediate size of the givenintermediate orifice 410 is no smaller than the size of the orificeimmediately downstream. In further such embodiments the orifice in thedownstream barrier 300 can be said to have a downstream orifice 310size, and the expanded size of each intermediate orifice 410 is nosmaller than the downstream orifice 310 size.

Again, when a series 500 of reconfigurable intermediate barriers 400 ispresent, each may serve to reduce the rate of discharge by providing anorifice having a given C_(d)A value, instead of a given size (althoughof course the C_(d)A value may be varied by varying the size). In suchembodiments, each given intermediate orifice 410 has a lesserintermediate C_(d)A value when the given intermediate barrier 400assumes the first intermediate configuration and a greater intermediateC_(d)A value when the given intermediate barrier 400 assumes the secondintermediate configuration. The lesser intermediate C_(d)A value issmaller than the greater intermediate C_(d)A value. The lesserintermediate C_(d)A value of the given intermediate barrier 400 issmaller than C_(d)A value of the orifice immediately downstream; and thegreater intermediate C_(d)A value is no smaller than the C_(d)A value ofthe orifice immediately downstream.

In further such embodiments, it can be said that the orifice in thedownstream barrier 300 has a downstream C_(d)A value; the lesserintermediate C_(d)A value of each intermediate barrier 400 is smallerthan the downstream C_(d)A value; and the greater intermediate C_(d)Avalue of each intermediate barrier 400 is no smaller than the downstreamC_(d)A value.

In another embodiment of the device comprising a series 500 ofreconfigurable intermediate barriers 400, the intermediate barriers 400are reconfigured by inserting or withdrawing them from the conduit 100.In such embodiments each intermediate orifice 410 is inserted into theconduit 100 when the intermediate barrier 400 assumes the firstintermediate configuration; and each intermediate orifice 410 iswithdrawn from the conduit 100 when the intermediate barrier 400 assumesthe second intermediate configuration. As described in otherembodiments, this allows the barriers 400 to simply be removed from thefluid flow instead of reconfiguring the barrier 400 to change thecharacteristics of the orifice 410.

A method is provided for controlling fluid flow through a conduit 100wherein the conduit 100 comprises an upstream orifice 210 and adownstream orifice 310, the method comprising: reconfiguring theupstream orifice 210 from a configuration in which the upstream orifice210 reduces the flow of the fluid more than does the downstream orifice310 to a configuration in which the upstream orifice 210 reduces theflow of the fluid no more than does the downstream orifice 310. The stepof reconfiguring the upstream orifice 210 may comprise increasing thesize of the upstream orifice 210. In some embodiments the step ofreconfiguring the upstream orifice 210 comprises changing the shape ofthe upstream orifice 210.

The step of reconfiguring the upstream orifice 210 may compriseincreasing the C_(d)A value of the orifice. In some embodiments of themethod the upstream orifice 210 is in an upstream barrier 200, and themethod comprises withdrawing the upstream barrier 200 from the conduit100. A method is provided for controlling fluid flow through a conduit100 comprising providing any of the fluid flow control structures 1described herein and reconfiguring at least one of the upstream barrier200 or an intermediate barrier 400 from its first configuration to itssecond configuration.

Turning now to the prophetic example in FIGS. 1-7, an embodiment of thestructure is provided as a conduit 100 comprising a series of orificeplates, each plate containing an orifice ranging in diameter from 1-36″in one-half inch increments. Thus there are 72 plates. The most upstreamplate contains no orifice (when closed it arrests flow completely). Thenext plate downstream comprises the smallest orifice (1″ in diameter).Each plate comprises two retractable sections 220. Each plate isrectangular, having a cross sectional area equal to or slightly greaterthan the cross-sectional area of the conduit 100. The orifice is in themiddle of each plate. Each retractable section 220 makes up half theplate and defines the perimeter of half of the orifice. Each retractablesection 220 is configured to be retracted from the conduit 100 in adirection opposite to the other retractable section 220 of the plate.This is achieved by means of a threaded rod bolt attached to theretractable section 220 by an anchor plate. A reversible electric motorwith a worm gear is used to move the threaded bolt in either direction,which causes the retractable section 220 to either retract from theconduit 100 or extend into the conduit 100. Once the retractablesections 220 meet, they cannot be extended into the conduit 100 anyfurther. Consequently, when the retractable sections 220 meet, theymutually define the orifice at its minimum size. Retracting theretractable sections 220 causes the effective size of the orifice toincrease. Because each orifice is only one-half inch narrower than thenext orifice downstream, if each retractable section 220 for a givenorifice plate is retracted only ¼″ then the next orifice downstreameffectively controls discharge from the conduit 100. Of course, eachplate is capable of being retracted to an extent that will allow itsorifice to assume a diameter that is at least equal to the diameter ofthe largest orifice in the structure (which would be the orifice in themost downstream plate).

In a specific embodiment, the series of barriers fit together to form aconduit 100 with a water tight connection throughout the structure. Bydoing so, flow through the most restrictive opening operates under inletcontrol and each subsequent less restrictive downstream opening is acomponent of the conduit 100 to convey the flow through the structure.Inlet control occurs when the control is immediately upstream of themost restrictive orifice and headwater depth and orifice configurationdetermine the amount of water entering the structure. Under inletcontrol conditions the amount of water entering the structure at themost restrictive opening is less than the conduit's 100 flow capacity.Consequently, the conduit 100 is flowing less than full.

C. Flood Control System

A flood control system 3000 that provides a volumetric discharge patternduring an ongoing storm event is provided. A general embodiment of thesystem comprises: a flow control structure 1000 configured to variablycontrol the rate of volumetric discharge from an intake point to arelease point; a computing device 1100 in control of the flow controlstructure 1000; a water level meter 1200 positioned to measure the waterlevel at the intake point and configured to transmit water level data tothe computing device 1100; a rain gauge 1300 configured to transmitrainfall data to the computing device 1100; and a machine-readable datastorage device 1400 comprising a plurality of storm flow functions thateach set a rate of volumetric discharge as a function of rainfall rate,wherein the machine-readable data storage device 1400 is configured tobe read by the computing device 1100. The flow control structure 1000may be any known in the art. In specific embodiments of the system theflow control structure 1000 is any one of the dynamic flood controlstructures 1 provided in this disclosure.

Either of both of the water level meter 1200 and the rain gauge 1300 maybe configured to transmit data they collect to the computing device 1100with very little delay between the time at which the data are collectedand the time at which the data are transmitted. Such “real time” datatransmission has the advantage of providing the computing device 1100with a constant stream of up to date information. Alternatively theremay be a small delay between data collection and transmission, so longas the delay allows the computing device 1100 to send instructions tothe flood control structure based on the data in a timely manner. Suchsmall delays have the advantage of saving energy by sending lessfrequent signals.

The computing device 1100 is specifically configured or programmed tocontrol the flow control structure 1000 in response to data from the oneor both of the rainfall gauge and the water level meter 1200 based on anongoing storm event. The computing device 1100 includes a bus or othercommunication mechanism for communicating information, and a processorcoupled with bus for processing information. The computing device 1100may also include a main memory, such as a random access memory (RAM) orother dynamic storage device, coupled to the bus for storing informationand instructions to be executed by the processor. Main memory also maybe used for storing temporary, variable or other intermediateinformation during execution of instructions to be executed by theprocessor. The computing device 1100 further includes a read only memory(ROM) or other static storage device coupled to the bus for storingstatic information and instructions for the processor.

The water level meter 1200 may be any that is known in the art.Non-limiting examples include sonic level sensors, guided-wave radarlevel sensors, pressure sensors, float-based level sensors, andvibrating short-fork sensors. The water level meter 1200 transmits waterlevel measurements to the computing device 1100. The water levelmeasurements may be transmitted periodically or constantly. In someembodiments of the system water level measurements are transmitted tothe computing device 1100 only after a rainfall event has been detectedvia the rain gauge 1300.

The rain gauge 1300 may be any known in the art that is capable ofautomated reporting. Non-limiting examples include a weighingprecipitation gauge, a tipping bucket rain gauge, an optical rain gauge,and an acoustic rain gauge. The rain gauge 1300 may transmit digital oranalog signals correlated to measured rainfall.

Each storm flow function is recorded on machine-readable media andallows a rate of volumetric discharge to be calculated from a rainfallrate. The rainfall rate may be any of various types of measurements.Non-limiting examples of the rainfall rate include a peak rate ofrainfall, and average rate of rainfall over the course of the event, anincremental rate of rainfall, an instantaneous rate of rainfall, arunning average rate of rainfall over a given period, and a total amount(depth) of rainfall over the course of the event.

The function may be derived from a modeled rainfall event, such as atwo-year storm event, a 25-year storm event, and a 100-year storm event.The function may be derived from an historic storm event. Any number offunctions may be recorded on the data storage device 1400. In a specificembodiment, the data storage device 1400 contains a function derivedfrom a two-year storm function, a 25-year storm function, and a 100-yearstorm function. The function may be a function of a pre-developmentrainfall event.

The intake point may be any point at which standing water would beexpected to be present during a rainfall event (regardless of whetherstanding water would be present at the point apart from the rainfallevent). Non-limiting examples of likely intake points include a drainageditch, a detention pond, a subterranean drain, a controlled section of awatercourse, and a storm drain. One specific embodiment of the intakepoint is a retention body 1500. The rain gauge 1300 will be positionedat a location that would be representative of the watershed.Non-limiting examples of suitable rain gauge 1300 positions include anynearby location in a static open body of water (such as a lake or apond), a location within the watershed open to the sky, or at a locationabout the same point in the grade of the structure.

An alternate embodiment of the flood control system 3000 comprises ameans for variably controlling the rate of volumetric discharge 1600from an intake point to a release point; a means for automated control1700 of the means for variably controlling the rate of volumetricdischarge 1600; means for measuring the water level 1800 at the intakepoint that transmits water level data to the means for automated control1700; means for measuring rainfall 1900 that transmits rainfall data tomeans for automated control 1700; and means for storing a plurality ofstorm flow functions 2000 that is readable by the means for automatedcontrol 1700. The means for variably controlling the rate of volumetricdischarge 1600 may be, for example, any of the flow control structures1000 described herein. The means for automated control 1700 of the meansfor variably controlling the rate of volumetric discharge 1600 may be,for example, any embodiment of the computing device described herein.The means for measuring the water level may be, for example, anyembodiment of the rain gauge described herein. The means for storing aplurality of storm flow functions 2000 that is readable by the means forautomated control 1700 may be, for example, any embodiment of themachine-readable data storage device described herein.

Turning now to the prophetic example in FIG. 8, an embodiment isprovided in which the intake point is at a downstream opening in adetention pond, which leads to the embodiment of the flood controlstructure provided in FIGS. 1-7, and which then leads to a dischargepipe and discharges into a receiving stream. The water level meter 1200is a float device proximate to the storm pipe which transmits waterlevel measurements to the computing device 1100 at one minute intervals.An electronic rain gauge 1300 accurate to about 0.001″ is connected tothe computing device 1100. The computing device 1100 is connected to andcontrols the flow control structure 1000. The computing device 1100communicates with a storage device (not shown) that calculates a rate ofdischarge that is equivalent to the pre-developed condition based ondata transmitted by the rain gauge 1300.

D. Flood Control Process

A flood control process is provided for achieving a predeterminedvolumetric discharge pattern in response to a rainfall event. A generalembodiment of the process comprises: receiving a rainfall measurementfrom an automated rain gauge 1300; reading a storm discharge function1410 from a machine-readable storage device 1400, wherein the stormdischarge function 1410 sets a rate of volumetric discharge as afunction of rainfall rate; computing a target rate of volumetricdischarge by plugging a rainfall rate value into the function 1410; andconfiguring a flow control structure 1000 to provide approximately thetarget rate of volumetric discharge from the body of water. In someembodiments of the method the predetermined volumetric discharge patternapproximates or recreates a discharge pattern for the local watershed ina natural or undeveloped state.

The process may comprise selecting a storm discharge function 1410 thatcorresponds to a measurement of storm severity. The measurement of stormseverity may be obtained from the automated rain gauge 1300 in someembodiments. For example, the total accumulated rainfall could be usedto measure storm severity. In another example, a predicted peak flowrate to or from a given body of water could be used to measure stormseverity. In another example the rainfall rate could be used to measurestorm severity. In embodiments of the method in which the stormdischarge function 1410 is selected based on storm severity, thedischarge function corresponds to a storm of comparable severity to theongoing storm. For example, the storage device may contain fourdischarge functions: one corresponding to a two-year 24-hour modelstorm, one corresponding to a 25-year 24-hour storm, and onecorresponding to a 100-year 24-hour storm. Such functions may beselected if the severity of the storm rises above certain thresholdlevels. Examples of such threshold levels include a threshold totalrainfall depth, a threshold predicted peak flow rate, and a thresholdrainfall rate.

In a prophetic example, during a storm event a function may be initiallyselected that corresponds to a storm that is less severe than a two-year24-hour storm. Upon receipt of a rainfall measurement indicating thatthe total rainfall depth threshold defining a two-year 24-hour storm hasbeen reached, a function corresponding to a storm more severe than atwo-year 24-hour storm may be selected. Upon receipt of a rainfallmeasurement indicating that the total rainfall threshold defining a25-year 24-hour storm has been reached, a function corresponding to astorm more severe than a 25-year 24-hour storm may be selected. Uponreceipt of a rainfall measurement indicating that the total rainfallthreshold defining a 100-year 24-hour storm has been reached, a function1410 corresponding to a storm more severe than a 100-year 24-hour stormmay be selected. The target rate of volumetric discharge may beconstantly calculated using the selected function 1410 and the rainfallrate, and the flow control structure 1000 may be constantly configuredto provide approximately the target rate of volumetric discharge fromthe body of water. As the severity of the storm changes, the selectedfunction 1410 changes.

In some versions of the process, once a function 1410 corresponding to astorm of a given severity has been selected, the process will not selecta function 1410 corresponding to a less severe storm during the courseof the storm, even if the severity of the storm decreases. In suchembodiments the function 1410 may change if the severity of the stormincreases, but not if it decreases. Such measures may often be necessarybecause it is inevitable that even the most severe storm will pass anddecrease in severity; however it may still be desirable to simulate thetrailing portion of the severe storm during this period, as opposed tosimulating a less severe storm.

The functions 1410 associating target discharge to rainfall rate may bebased on the hydrologic parameters of the watershed. In certainembodiments of the process some or all of the hydrologic parameters maybe stored in a “junction summary file” on a machine-readable storagedevice 1400. For example, such parameters may include a weighted curvenumber, a time of concentration, and the area of watershed. The curvenumber (also known as runoff curve number) is based on the permeabilityof the groundcover of the watershed, and represents the rate of surfacerunoff flow (volume per time) as a function of total rainfall (depth);the runoff curve number will in some cases be based on thepre-development watershed. Time of concentration represents the timerequired to for water to flow from the most hydraulically remotelocation in the watershed to a drainage point (in this case the drainagepoint is the body of water at the intake point of the controlstructure).

Some embodiments of the process allow a user to select the appropriatefunction 1410. For example, if the severity of an ongoing stormincreases above a threshold (for example, more severe than a two-year24-hour storm but less than or equal to a 25-year 24-hour storm) theuser may be presented with the option to continue to use the function1410 corresponding to the less severe storm, or to switch to thefunction corresponding to the more severe storm. In another example, theseverity of the ongoing storm may be below a threshold, and the user ispresented with the option to use the function 1410 corresponding to amore severe storm. This option to select the function 1410 associatedwith the more severe storm event could be used in cases in which therequired volume of the upstream reservoir is not achievable due to somehardship, such as a limited amount of area available for storm waterdetention. Simulating a more severe storm will increase flow from theupstream reservoir.

Some embodiments of the process comprise configuring the flow controlstructure 1000 to provide a constant drainage rate of discharge afterthe storm event is complete. More specific embodiments of the processcomprise receiving a later rainfall measurement from the rain gauge1300, wherein the later rainfall measurement is below a threshold valueindicative of the termination of the storm event. The threshold valuemay be zero, or about zero. The constant rate of discharge will besufficient to prevent adverse impacts downstream of the flow controlstructure 1000. The constant flow rate may be based on at least one ofthe capacity of the downstream receiving body or bodies, the ecologicalsensitivity of the downstream receiving body or bodies, the erosionalsensitivity of the downstream receiving body or bodies, water rights inthe downstream receiving body or bodies, and other environmentalsensitivities in the downstream receiving body or bodies. Suchembodiments allow the upstream source water body to be drained withoutadverse downstream impacts. In some embodiments of the process theconstant drainage rate will be provided until the upstream source waterbody reaches a predetermined depth. In some cases the predetermineddepth may be zero, in which case the upstream source water body will bedrained.

The water level gauge, source point, machine-readable data storagedevice 1400, storm flow function 1410, and flow control structure 1000may be any that are described herein as suitable for the flood controlsystem.

Turning now to the prophetic examples of FIGS. 9-12, the storm flowprofiles from a model system are shown for four different flood events.These profiles are from an actual drainage basin. In each figure, thetop frame compares uncontrolled post-developed discharge topre-developed discharge. FIGS. 9-11 show the calculated discharge overtime for modeled storm events in the system (two-year, 25-year, and100-yer storms) and FIG. 12 shows actual results from an actual rainfallevent for a pre-development storm event compared to the same rainfallmodeled for post-development. As can be seen in all of FIGS. 9-12,uncontrolled post-development discharge is much more intense and occursover a much shorter period of time than either the pre-developmentdischarge or controlled post-development discharge. The middle frames ofFIGS. 9-12 show a comparison of post-developed discharge controlled by astatic flood control structure to pre-developed discharge. It should benoted that, although a static control structure provides significantlyattenuated discharge when compared to uncontrolled post-developmentpatterns, it significantly differs from pre-development dischargepatterns and discharge patterns when the embodiment of the flood controlprocess is used. The bottom frames of FIGS. 9-12 show a comparison ofpost-developed discharge controlled according to an embodiment of theflood control method provided in this application to pre-developeddischarge. Note that the bottom frame of FIG. 11 displays elevated flowduring recession period used the embodiment of the process over thepre-development model due to the selection of a function correspondingto a more severe storm. Note also that the elevated flow at the tail-endof the storm in bottom frame of FIG. 12 is due to the processconfiguring the flow control structure 1000 to provide constantdischarge after the end of the storm event so as to reduce the waterlevel in the upstream source body. Apart from the noted deviations, theembodiment of the process closely approximates natural flow in all fourexamples. Note that all prophetic examples model a static controlstructure designed not to exceed the pre-developed peak flow rate forany of the two year, 25-year, and 100-year 24 hour design storms. Thisexample demonstrates that static control structures, even when designedfor multiple design storms, are not capable of attenuating real stormpeak flow rates. It also demonstrates that static control structures canshift the time at which the storm peaks, causing a delay in the peakflow rate, which can lead to downstream flooding.

E. Conclusions

It is to be understood that any given elements of the disclosedembodiments of the invention may be embodied in a single structure, asingle step, a single substance, or the like. Similarly, a given elementof the disclosed embodiment may be embodied in multiple structures,steps, substances, or the like. The foregoing description illustratesand describes the processes, machines, manufactures, compositions ofmatter, and other teachings of the present disclosure. Additionally, thedisclosure shows and describes only certain embodiments of theprocesses, machines, manufactures, compositions of matter, and otherteachings disclosed, but, as mentioned above, it is to be understoodthat the teachings of the present disclosure are capable of use invarious other combinations, modifications, and environments and iscapable of changes or modifications within the scope of the teachings asexpressed herein, commensurate with the skill and/or knowledge of aperson having ordinary skill in the relevant art. The embodimentsdescribed hereinabove are further intended to explain certain best modesknown of practicing the processes, machines, manufactures, compositionsof matter, and other teachings of the present disclosure and to enableothers skilled in the art to utilize the teachings of the presentdisclosure in such, or other, embodiments and with the variousmodifications required by the particular applications or uses.Accordingly, the processes, machines, manufactures, compositions ofmatter, and other teachings of the present disclosure are not intendedto limit the exact embodiments and examples disclosed herein. Anysection headings herein are provided only for consistency with thesuggestions of 37 C.F.R. §1.77 or otherwise to provide organizationalqueues. These headings shall not limit or characterize the invention(s)set forth herein.

I claim:
 1. A structure 1000 for controlling liquid flow, the structurecomprising: (a) a conduit 100 through which the liquid flows; (b) adownstream barrier 300 in the conduit 100, the downstream barrier 300comprising a downstream orifice 310; (c) an upstream reconfigurablebarrier 200 in the conduit 100, the upstream barrier 200 comprising (i)an upstream orifice 210, (ii) two retractable sections 220 which, whenretracted, increase the width of the upstream orifice 210 to be greaterthan the width of the downstream orifice 310, and (iii) wherein theupstream barrier 200 is capable of assuming a contracted upstreamconfiguration and a retracted upstream configuration; (d) a plurality ofintermediate reconfigurable barriers 400 in the conduit 100 between theupstream barrier 200 and the downstream barrier 300, each saidintermediate barrier 400 comprising (i) an intermediate orifice 410 (ii)two retractable sections 220 which, when retracted, increase the widthof the intermediate orifice 410 to be greater than the width of thedownstream orifice 310, and (iii) wherein each intermediate barrier 400is capable of assuming a contracted intermediate configuration and aretracted intermediate configuration; wherein the size of a givenintermediate orifice 410 when the intermediate barrier 400 is in thecontracted configuration is smaller than the size of the orificeimmediately downstream; and wherein the size of a given intermediateorifice 410 is no smaller than the size of the orifice immediatelydownstream when the intermediate barrier 400 is in the intermediateconfiguration.
 2. A structure 1000 for controlling the flow of a fluid,the structure comprising: (a) a fluid conduit 100 through which thefluid flows; (b) an upstream reconfigurable barrier 200 in the conduit100, the upstream barrier 200 comprising an upstream orifice 210, andthe upstream barrier 200 capable of assuming a first upstreamconfiguration and a second upstream configuration, wherein the upstreamorifice 210 has a lesser upstream C_(d)A value when the upstream barrier200 assumes the first upstream configuration, the upstream orifice 210has a greater upstream C_(d)A value when the upstream barrier 200assumes the second upstream configuration, and the lesser upstreamC_(d)A value is smaller than the greater upstream C_(d)A value; (c) adownstream barrier 300 in the conduit 100, the downstream barrier 300comprising a downstream orifice 310, wherein the downstream orifice 310has a downstream C_(d)A value, the lesser upstream C_(d)A value issmaller than the downstream C_(d)A value, and the greater upstreamC_(d)A value is no smaller than the downstream C_(d)A value; wherein theupstream orifice 210 reduces the flow of the fluid more than does thedownstream orifice when the upstream barrier 200 assumes the firstconfiguration, and wherein the upstream orifice reduces the flow of thefluid no more than does the downstream orifice 310 when the upstreambarrier 200 assumes the second configuration; and wherein C_(d) is thecoefficient of discharge and A is the cross-sectional area of the givenorifice.
 3. The structure of claim 2, wherein (a) the upstream orifice210 is a contracted upstream size when the upstream barrier 200 assumesthe first upstream configuration; (b) the upstream orifice 210 is anexpanded upstream size when the upstream barrier 200 assumes the secondupstream configuration; (c) the downstream orifice 310 is a downstreamorifice size; (d) the contracted upstream size is smaller than theexpanded upstream size; (e) the contracted upstream size is smaller thanthe downstream orifice size; and (f) the expanded upstream size is nosmaller than the downstream orifice size.
 4. The structure of claim 2,wherein the upstream reconfigurable barrier 200 is inserted into theconduit 100 in the first upstream configuration and wherein the upstreamreconfigurable barrier 200 is withdrawn from the conduit 100 in thesecond upstream configuration.
 5. The structure of claim 2, comprising:(a) an intermediate reconfigurable barrier 400 in the conduit 100between the upstream barrier 200 and the downstream barrier 300, theintermediate barrier 400 comprising an intermediate orifice 410, and theintermediate barrier 400 capable of assuming a first intermediateconfiguration and a second intermediate configuration; (b) wherein theintermediate orifice 410 reduces the flow of the fluid more than doesthe downstream orifice 310 when the intermediate barrier 400 assumes thefirst intermediate configuration; (c) wherein the intermediate orifice410 reduces the flow of the fluid no more than does the downstreamorifice 310 when the intermediate barrier 400 assumes the secondintermediate configuration; and (d) wherein the upstream orifice 210reduces the flow of the fluid more than does the intermediate orifice410 when the upstream barrier 200 assumes the first upstreamconfiguration and the intermediate barrier 400 assumes the firstintermediate configuration; and (e) wherein the upstream orifice 210reduces the flow of the fluid no more than does the intermediate orifice410 when the upstream barrier 200 assumes the second upstreamconfiguration and the intermediate orifice 410 assumes the firstintermediate configuration.
 6. The structure of claim 5, wherein (a) theupstream orifice 210 is a contracted upstream size when the upstreambarrier 200 assumes the first upstream configuration; (b) the upstreamorifice 210 is an expanded upstream size when the upstream barrier 200assumes the second upstream configuration; (c) the downstream orifice310 is a downstream orifice size; (d) the intermediate orifice 410 is acontracted intermediate size when the intermediate barrier 400 assumesthe first intermediate configuration; (e) the intermediate orifice 410is an expanded intermediate size when the intermediate barrier 400assumes the second intermediate configuration; (f) the contractedupstream size is smaller than the expanded upstream size; (g) thecontracted intermediate size is smaller than the expanded intermediatesize; (h) the contracted upstream size is smaller than the contractedintermediate size; (i) the contracted intermediate size is smaller thanthe downstream orifice size; (j) the expanded upstream size is nosmaller than the downstream orifice size; (k) the expanded upstream sizeis no smaller than the contracted intermediate size; and (l) theexpanded intermediate size is no smaller than the downstream orificesize.
 7. The structure of claim 5, wherein the intermediatereconfigurable barrier 400 is inserted into the conduit 100 in the firstintermediate configuration and wherein the intermediate reconfigurablebarrier 400 is withdrawn from the conduit 100 in the second intermediateconfiguration.
 8. The structure of claim 5, wherein: (a) theintermediate orifice 410 has a lesser intermediate C_(d)A value when theintermediate barrier 400 assumes the first intermediate configuration;(b) the intermediate orifice 410 has a greater intermediate C_(d)A valuewhen the intermediate barrier 400 assumes the second intermediateconfiguration; (c) the lesser intermediate C_(d)A value is smaller thanthe greater intermediate C_(d)A value; (d) the lesser upstream C_(d)Avalue is smaller than the lesser intermediate C_(d)A value; (e) thelesser intermediate C_(d)A value is smaller than the downstream C_(d)Avalue; (f) the greater upstream C_(d)A value is no smaller than thelesser intermediate C_(d)A value; and (g) the greater intermediateC_(d)A value is no smaller than the downstream C_(d)A value.
 9. Thestructure of claim 2, comprising a series 500 of reconfigurableintermediate barriers 400 between the upstream and downstream barriers300 each comprising an intermediate orifice 410, each of theintermediate barriers 400 having a first intermediate configuration anda second intermediate configuration, wherein a given intermediateorifice 410 reduces the flow of the fluid more than does the orificeimmediately downstream when the given intermediate barrier 400 assumesthe first intermediate configuration, and wherein the given intermediateorifice 410 reduces the flow of the fluid no more than does the orificeimmediately downstream when the given intermediate barrier 400 assumesthe second configuration.
 10. The structure of claim 9, wherein: (a)each intermediate orifice 410 is a contracted intermediate size when theintermediate barrier 400 assumes the first intermediate configuration;(b) each intermediate orifice 410 is an expanded intermediate size whenthe intermediate barrier 400 assumes the second intermediateconfiguration; (c) the contracted intermediate size of a givenintermediate orifice 410 is smaller than the size of the orificeimmediately downstream; and (d) the expanded intermediate size of thegiven intermediate orifice 410 is no smaller than the size of theorifice immediately downstream; wherein in the downstream orifice 310has a downstream orifice 310 size, and wherein the expanded size of eachintermediate orifice 410 is no smaller than the downstream orifice 310size.
 11. The structure of claim 9, wherein: (a) each intermediateorifice 410 is inserted into the conduit 100 when the intermediatebarrier 400 assumes the first intermediate configuration; and (b) eachintermediate orifice 410 is withdrawn from the conduit 100 when theintermediate barrier 400 assumes the second intermediate configuration.12. The structure of claim 9, wherein: (a) each given intermediateorifice 410 has a lesser intermediate C_(d)A value when the givenintermediate barrier 400 assumes the first intermediate configuration;(b) each given intermediate orifice 410 has a greater intermediateC_(d)A value when the given intermediate barrier 400 assumes the secondintermediate configuration; (c) the lesser intermediate C_(d)A value issmaller than the greater intermediate C_(d)A value; (d) the lesserintermediate C_(d)A value is smaller than the C_(d)A value of theorifice immediately downstream; and (e) the greater intermediate C_(d)Avalue is no smaller than the C_(d)A value of the orifice immediatelydownstream.
 13. The structure of claim 12, wherein: (a) the lesserintermediate C_(d)A value is smaller than the downstream C_(d)A value;and (b) the greater intermediate C_(d)A value is no smaller than thedownstream C_(d)A value.
 14. The structure of claim 2, wherein (a) theupstream orifice 210 is a contracted upstream size when the upstreambarrier 200 assumes the first upstream configuration; (b) the upstreamorifice 210 is an expanded upstream size when the upstream barrier 200assumes the second upstream configuration; (c) the upstream orifice 210is maximally contracted in the first upstream configuration; and (d) theupstream orifice 210 is maximally expanded it the second upstreamconfiguration.
 15. The structure of claim 2, wherein the upstreamreconfigurable barrier 200 comprises a plurality of retractable sections220.
 16. A flood control system 3000 for providing a predeterminedvolumetric discharge pattern in response to a storm event, the systemcomprising: (a) the flow control structure 1000 of claim 2; (b) acomputing device 1100 in control of the flow control structure 1000 bycontrolling the configuration of the upstream reconfigurable barrier;(c) a water level meter 1200 positioned to measure the water level atthe intake point and configured to transmit water level data to thecomputing device 1100; (d) a rain gauge 1300 configured to transmitrainfall data to the computing device 1100; (e) and a machine-readabledata storage device 1400 comprising a plurality of storm flow functionsthat each set a rate of volumetric discharge as a function of rainfallrate, wherein the machine-readable data storage device 1400 isconfigured to be read by the computing device
 1100. 17. A structure 1000for controlling the flow of a fluid, the structure comprising: (a) afluid conduit 100 through which the fluid flows; (b) an upstreamreconfigurable barrier 200 in the conduit 100, the upstream barrier 200comprising an upstream orifice 210, and the upstream barrier 200 capableof assuming a first upstream configuration and a second upstreamconfiguration; (c) a downstream barrier 300 in the conduit 100, thedownstream barrier 300 comprising a downstream orifice 310; wherein theupstream orifice 210 reduces the flow of the fluid more than does thedownstream orifice when the upstream barrier 200 assumes the firstconfiguration, and wherein the upstream orifice reduces the flow of thefluid no more than does the downstream orifice 310 when the upstreambarrier 200 assumes the second configuration; and wherein the upstreamreconfigurable barrier 200 comprises two retractable sections 220 which,when retracted, increase the size of the orifice to be greater than thewidth of the downstream orifice
 310. 18. The structure of claim 17,wherein the two retractable sections 220 are retracted at leastpartially from the conduit 100 in the second upstream configuration andare fully extended into the conduit 100 in the first upstreamconfiguration.
 19. The structure of claim 17, wherein: (a) tworetractable sections 220 are retracted at least partially from theconduit 100 in the second upstream configuration and are fully extendedinto the conduit 100 in the first upstream configuration; and (b) eachof the two retractable sections 220 defines a portion of the perimeterof the upstream orifice 210.